Electric compressor

ABSTRACT

The present invention provides an electric compressor which enables prescribed insulation performance to be ensured even if poly alkyl glycol type lubricating oils are used. The electric compressor is provided with an insulating cover which is provided so as to cover a connection section between a terminal body and a lead wire on the motor side, and on a surface on the side of a first insulating member of the insulating cover, there is provided a cutoff section which cuts off a leakage path by abutting against the first insulating member, whereby the leakage path between the first insulating member and the insulating cover is cut off.

TECHNICAL FIELD

The present invention relates to an electric compressor provided with amotor for driving a compression section, a motor driving circuit fordriving the motor, and a sealed terminal for electrically connecting themotor and the motor driving circuit.

BACKGROUND ART

As an electric compressor of this kind, there has hitherto been known anelectric compressor which is provided with a compression section forcompressing a cooling medium, a motor for driving the compressionsection, a motor driving circuit for driving the motor, and a sealedterminal which is provided in a partition wall for partitioning a spaceon the motor side and a space on the motor driving circuit side and isintended for electrically connecting a lead wire on the motor side and alead wire on the motor driving circuit side (refer to Patent Literature1, for example).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Publication 11-324920

SUMMARY OF THE INVENTION Problems to be Solved by The Invention

In an open-type compressor in which the driving torque is transmittedfrom outside, poly alkyl glycol (PAG) type lubricating oils are used tolubricate sliding parts in the housing. However, because poly alkylglycol type lubricating oils have low electrical insulation performanceand it is impossible to use these lubricating oils in the electriccompressor, expensive polyol ester (POE) type lubricating oils are usedin the above-described electric compressor in which a motor isincorporated. As a result of this, it is necessary to use differentkinds of lubricating oils in open-type compressors and theabove-described electric compressor and, therefore, work such asmaintenance becomes complicated.

The object of the present invention is to provide an electric compressorwhich enables prescribed insulation performance to be ensured even ifpoly alkyl glycol type lubricating oils are used.

Means for Solving The Problem

In order to achieve the above object, the present invention provides anelectric compressor which includes: a compression section forcompressing a cooling medium, a motor for driving the compressionsection, a motor driving circuit for driving the motor, a sealedterminal which is provided in a partition wall for partitioning a spaceon the motor side and a space on the motor driving circuit side and isintended for electrically connecting a lead wire on the motor side and alead wire on the motor driving circuit side, and an insulating coverprovided so as to cover a connection section between the sealed terminaland the lead wire on the motor side. In this electric compressor, theinsulating cover has a cutoff section which is provided on a surface onthe partition wall side and cuts off a leakage path by abutting againsta member on the partition wall side.

As a result of this, because the cutoff section provided in theinsulating cover abuts against the member on the partition wall side, aleakage path between the member on the partition wall side and theinsulating cover is cut off.

Effects of The Invention

According to the present invention, it is possible to cut off a leakagepath between the member on the partition wall side and the insulatingcover and, therefore, it is possible to ensure prescribed insulationperformance even if poly alkyl glycol type lubricating oils are used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of an electric compressor in anembodiment of the present invention.

FIG. 2 is a sectional view of a sealed terminal.

FIG. 3 is an exploded perspective view of the sealed terminal.

FIG. 4 is a partial sectional view of the sealed terminal.

FIG. 5 is a partial sectional view of a sealed terminal showing anotherexample of an insulating cover.

FIG. 6 is a partial sectional view of a sealed terminal showing anotherexample of a cutoff section.

FIG. 7 is a partial sectional view of a sealed terminal showing anotherexample of a cutoff section.

FIG. 8 is a partial sectional view of a sealed terminal showing anotherexample of a cutoff section.

FIG. 9 is a partial sectional view of a sealed terminal showing anotherexample of an air vent portion.

FIG. 10 is a partial sectional view of a sealed terminal showing anotherexample of an air vent portion.

PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1 to 4 show an embodiment of the present invention. The electriccompressor of the present invention is a scroll-type electric compressorwhich is provided with a housing 10 formed in cylindrical shape, acompression section 20 for compressing a cooling medium, a motor 30 fordriving the compression section 20, and a driving circuit section 40 asa motor driving circuit for performing the operation control of themotor 30, and for example, HFC-134a and carbon dioxide or the like areused as a cooling medium.

The housing 10 is composed of a first housing 11 in which thecompression section 20 is housed, a second housing 12 in which the motor30 is housed, and a third housing 13 in which the driving circuitsection 40 is housed.

The first housing 11 is such that one end surface thereof is closed andthe other end surface thereof is joined to one end surface of the secondhousing 12. A cooling medium discharge port, which is not shown, isprovided on a peripheral surface of the first housing 11 on the side ofthe one end surface.

The second housing 12 is such that the side of one end surface thereofis joined to the first housing 11 and the side of the other end surfacethereof is joined to one end surface of the third housing 13.

The first housing 11 and the second housing 12 are joined together by abolt 14 via a center plate, which will be described later, for rotatablysupporting the side of one end of a driving shaft, which will bedescribed later, for driving the compression section 20.

The third housing 13 is such that the side of one end surface thereof isjoined to the second housing 12 and the side of the other end surfacethereof is closed by a closing plate 15 so as to be openable. A coolingmedium suction port is provided on a peripheral surface of the thirdhousing 13 on the side of one end surface thereof. Furthermore, thethird housing 13 is such that the interior thereof is partitioned by apartition wall 13 a into the side of one end surface including thecooling medium suction port and the side of the other end surface, andthe third housing is provided with a driving circuit housing chamber 13b for housing the driving circuit section 40 and a cooling mediumsuction chamber 13 c in communication with the motor 30 side.

The compression section 20 has a fixed scroll member 21 fixed to theside of one end of the first housing 11 and a rotating scroll member 22provided on the side of the other end of the first housing 11 so as tobe rotatable with respect to the fixed scroll member 21.

The fixed scroll member 21 is formed from a member in the shape of adisk provided so as to divide the interior of the first housing 11, anda swirl body 21 a is provided on a surface on the rotating scroll member22 side. In the radially middle part of the fixed scroll member 21,there is provided a cooling medium discharge hole 21 b for discharging acooling medium compressed in the compression section 20. A coolingmedium discharge chamber 11 a is provided between one end surface in thefirst housing 11 and the fixed scroll member 21 so that a cooling mediumdischarged from the cooling medium discharge port flows into the coolingmedium discharge chamber 11 a.

The rotating scroll member 22 is such that a convoluted body 22 a isprovided on the surface thereof on the fixed scroll member side, and tothe surface on the opposite side, there is connected, via a driving bush24, the side of one end of a driving shaft 23 for transmitting thetorque of the motor 30.

The driving shaft 23 is provided so as to extend along the central axisof the second housing 12. The driving shaft 23 is provided in such amanner that a connection section 23 a to the driving bush 24 iseccentric from the rotation center of the driving shaft 23. Also, thedriving shaft 23 is such that the side of one end thereof is rotatablysupported by a center plate 25 provided between the compression section20 and the motor 30 via a ball bearing 26 and the side of the other endthereof is rotatably supported via a bearing 12 a (a ball bearing 27)provided on the side of the other end surface of the second housing 12.That is, the driving shaft 23 is rotated by the motor 30 and is adaptedto cause the rotating scroll member 22 to rotate on a prescribedcircular orbit.

The center plate 25 is provided so as to divide the space on thecompression section 20 side and the space on the motor 30 side in thehousing 10, and there is provided a communication hole for providingcommunication between the space on the compression section 20 side andthe space on the motor 30 side. Also, the center plate 25 is providedwith a flanged portion 25 a extending in the circumferential directionof an outer circumferential surface so that the flanged portion 25 abecomes sandwiched between the first housing 11 and the second housing12.

Between the rotating scroll member 22 and the center plate 25, there isprovided a rotating position regulating mechanism 28 consisting of pinswhich are each fixed to the rotating scroll member 22 and the centerplate 25 in order to regulate the rotating position of rotating scrollmember 22, and a connecting member for connecting the pins together.

The motor 30 is composed of a three-phase induction motor and the likeand has a rotor 31 formed from a permanent magnet fixed to the drivingshaft 23, and a stator 32 which is provided so as to surround the rotor31 and is fixed in the second housing 12.

The driving circuit section 40 is composed of an inverter circuit 41having, on a substrate, power semiconductor elements 41 a as a pluralityof heat generating parts, a power circuit part 42, such as a smoothingcapacitor and a noise filter, a control section 43 of a microcomputerconfiguration, and the like. The driving circuit section 40 is housed inthe driving circuit housing chamber 13 b and is fixed in the drivingcircuit housing chamber 13 b by use of a molded resin 44.

This motor compressor is provided with three sealed terminals 50provided in the partition wall 13 a positioned below the cooling mediumsuction chamber 13 c and intended for supplying the electrical powerfrom the inverter circuit 41 to the winding of the stator 32.

Each of the sealed terminals 50 is composed of a terminal body 51inserted into a through hole 13 d provided in the partition wall 13 a, afixing nut 52 for fixing the terminal body 51 to the partition wall 13a, a first insulating member 53 to be interposed on the second housing12 side of the partition wall 13 a, a second insulating member 54 to beinterposed between the fixing nut 52 and the partition wall 13 a, ajoining nut 55 which is connectably provided to an end portion of theterminal body 51 on the driving circuit housing chamber 13 b side and towhich a lead wire 45 on the driving circuit housing chamber 13 b side isjoined by welding, and an insulating cover 56 for covering a connectionsection 51 c between the terminal body 51 and a lead wire 33 on themotor 30 side. Here, the lead wire 45 on the driving circuit housingchamber 13 b side is formed from a copper-bearing material.

The terminal body 51 is made of an iron-bearing metal and is such thatan end portion thereof on the second housing 12 side is provided with aflange 51 a and an end portion thereof on the driving circuit housingchamber 13 b side is provided with a male threaded portion 51 b and itis ensured that the lead wire 33 on the motor 30 side is connected tothe end portion on the second housing 12 side by caulking or the like.The terminal body 51 is attached to the partition wall 13 a by screwingthe fixing nut 52 to the male threaded portion 51 b, with the firstinsulating member 53 interposed on the second housing 12 side of thepartition wall 13 a and the second insulating member 54 interposed onthe driving circuit housing chamber 13 b side of the partition wall 13a.

The first insulating member 53 and the second insulating member 54 areeach formed from a member having insulating properties, such as ceramicsand synthetic resins. The first insulating member 53 is provided withthree holes 53 a, through each of which three terminal bodies 51 areinserted, and one first insulating member 53 is used for the threeterminal bodies 51. The second insulating member 54 is provided with ahole 54 a through which the terminal body 51 is inserted, and one secondinsulating member 54 is used for one terminal body 51.

The joining nut 55 is made of a copper-bearing metal and is formed inthe shape of a cap nut which is such that the side of one end thereof isclosed. The joining nut 55 is provided with a weld portion 55 a so as toprotrude from the side of one end and it is ensured that the lead wire45 on the driving circuit housing chamber 13 b side is jointed to theweld portion 55 a by welding.

The insulating cover 56 is made of a material having elasticity andinsulating properties, such as rubber, and is formed so as to coversubstantially the whole surface of one end surface of the firstinsulating member 53. The insulating cover 56 is provided with threeholes 56 a through which the three lead wires 33 on the motor 30 sideare each to be inserted, and it is ensure that the insulating cover 56covers the connection sections 51 c of the three terminal bodies 51 andthe lead wires 33, with the lead wires 33 inserted through the holes 56a. On the surface of the insulating cover 56 on the first insulatingmember 53 side, there is provided a cutoff section 56 b which isprovided so as to extend to the first insulating member 53 side alongthe outer circumferential portion and cuts off a leakage path byabutting against the first insulating member 53. The cutoff section 56 bis provided with an air vent hole 56 c as an air vent portion forventing the air between the insulating cover 56 and the first insulatingmember 53 during the evacuation of the connected cooling medium circuit.The air vent hole 56 c is provided by notching an end portion of thecutoff section 56 b in the shape of the letter V and is formed in such amanner that the opening area becomes not more than 10 square millimeterswhen attached to the terminal body 51.

In the electric compressor configured as described above, the drivingshaft 23 is rotated by passing a current to the motor 30, whereby in thecompression section 20 the rotating scroll member 22 performs a rotatingmotion with respect to the fixed scroll member 21. As a result of this,a cooling medium which flows into the housing 10 from the cooling mediumsuction port cools each of power semiconductor elements of the invertercircuit 41 of the driving circuit section 40 via the partition wall 13 aof the cooling medium suction chamber 13 c and cools the motor 30 byflowing through the interior of the second housing 12. The coolingmedium which has flown through the interior of the second housing 12flows between the rotating scroll member 22 and the center plate 25 viathe communication hole of the center plate 25, cools the rotatingposition regulating mechanism 50 and then flows into the compressionsection 20. The cooling medium compressed in the compression section 20flows from the cooling medium discharge hole 21 b into the coolingmedium discharge chamber 11 a and is discharged from the cooling mediumdischarge port.

In each of the sealed terminals 50, in performing the work to connectthe lead wire 45 on the driving circuit housing chamber 13 b side, thejoining nut 55 is screwed to the male threaded portion 51 b, with theterminal body 51 attached to the partition wall 13 a, and the lead wire45 is joined to the weld portion 55 a of the joining nut 55 by welding.

Because the connection section 51 c between the terminal body 51 and thelead wire 33 is covered with the insulating cover 56, the leakage to thehousing 10 side is cut off and insulating. Also, because the cutoffsection 56 b of the insulating cover 56 abuts against the firstinsulating member 53 along the outer circumferential portion thereof, aleakage path between the first insulating member 53 and the insulatingcover 56 is cut off. Furthermore, because the air vent hole 56 c isprovided in the cutoff section 56 b, in mounting the sealed terminal 50,the air between the first insulating member 53 and the insulating cover56 is discharged to outside from the air vent hole 56 c during theevacuation of the cooling medium circuit. The air vent hole 56 c isformed in such a manner that the opening areas is not more than squaremillimeters and, therefore, it is possible to ensure prescribedinsulation performance.

According to the electric compressor of this embodiment, the insulatingcover 56 is provided so as to cover the connection section 51 c betweenthe terminal body 51 and the lead wire 33 on the motor 30 side, and thecutoff section 56 b which cuts off a leakage path by abutting againstthe first insulating member 53 is provided on the surface of theinsulating cover 56 on the first insulating member 53 side. As a resultof this, it is possible to cut off a leakage path between the firstinsulating member 53 and the insulating cover 56 by the cutoff section56 b and, therefore, it is possible to ensure prescribed insulationperformance even if poly alkyl glycol type lubricating oils are used.

The cutoff section 56 b is provided with the air vent hole 56 c forventing the air between the insulating cover 56 and the first insultingmember 53. As a result of this, it is possible to vent the air betweenthe insulating cover 56 and the first insulting member 53 during theevacuation of the cooling medium path and, therefore, it becomespossible to positively carry out the evacuation of the cooling mediumcircuit.

The opening area of the air vent hole 56 c is not more than 10 squaremillimeters. As a result of this, it is possible to ensure prescribedinsulation performance and, therefore, this enables prescribedinsulation performance to be ensured and positive evacuation to beperformed.

The insulating cover 56 is provided integrally with the plurality ofterminal bodies 51. As a result of this, it is possible to insulate theconnection sections 51 c between the plurality of terminal bodies 51 andthe lead wire 33 by one insulating cover 56 and, therefore, it becomespossible to reduce the number of parts.

Although in the above-described embodiment, the insulating cover 56 isprovided integrally with the plurality of terminal bodies 51, even whenone insulating cover 57 is provided for one terminal body 51 as shown inFIG. 5, it is possible to ensure insulation performance in the samemanner as in the above-described embodiment.

Although in the above-described embodiment, the cutoff section 56 b isprovided so as to extend to the first insulating member 53 side alongthe outer circumferential portion of the insulating cover 56, even whena cutoff section 56 d is provided so as to protrude from the outercircumferential portion side of the insulating cover 56 on the firstinsulating member 53 side as shown in FIG. 6, it is possible to obtainthe same effect as in the above-described embodiment.

Even if as shown in FIG. 7, a cutoff section is composed of a wall 53 bwhich extends to the insulating cover 56 side along the outercircumferential portion of one end surface of the first insulatingmember 53 and an extending portion 56 e of the insulating cover 56 whichabuts against the inner surface of the wall 53 b of the first insulatingmember 53, it is possible to obtain the same effect as in theabove-described embodiment.

Even if a cutoff section is composed of a ring-shaped packing 56 fprovided along the outer circumferential portion between the firstinsulating member 53 and the insulating cover 56 as shown in FIG. 8, itis possible to obtain the same effect as in the above-describedembodiment.

Although in the above-described embodiment, the air vent hole 56 c as anair vent portion for venting the air between the insulating cover 56 andthe first insulating member 53 is formed by notching the end portion ofthe cutoff section 56 b in the form of the letter V, it is possible toobtain the same effect as in the above-described embodiment by providinga round air vent hole 56 g having an opening area of not more than 10square millimeters in the cutoff section 56 b as shown ion FIG. 9.

Also, as shown in FIG. 10, by providing a protrusion 56 h in an endportion of the cutoff section 56 b and configuring an air vent portionso that a gap whose opening area is not more than 10 square millimetersis formed in the vicinity of the protrusion 56 h when the cutoff section56 b is caused to abut against the first insulating member 53, it ispossible to obtain the same effect as in the above-described embodiment.

DESCRIPTION OF THE SYMBOLS

13 a: partition wall, 20: compression section, 30: motor, 33: lead wire,40: driving circuit section, 45: lead wire, 50: sealed terminal, 51:terminal body, 51 c: connection section, 53: first insulating member, 53b: wall, 56: insulating cover, 56 b: cutoff section, 56 c: air venthole, 56 d: cutoff section, 56 e: extending portion, 56 f: packing, 56g: air vent hole, 56 h: protrusion.

1. An electric compressor comprising: a compression section forcompressing a cooling medium; a motor for driving the compressionsection; a motor driving circuit for driving the motor; a sealedterminal which is provided in a partition wall for partitioning a spaceon the motor side and a space on the motor driving circuit side and isintended for electrically connecting a lead wire on the motor side and alead wire on the motor driving circuit side; and an insulating coverprovided so as to cover a connection section between the sealed terminaland the lead wire on the motor side, wherein the insulating cover has acutoff section which is provided on a surface on the partition wall sideand cuts off a leakage path by abutting against a member on thepartition wall side.
 2. The electric compressor according to claim 1,further comprising air vent portions to vent the air in a space formedbetween the insulating cover and the member on the partition wall side.3. The electric compressor according to claim 2, wherein the air ventportions are provided in the cutoff section and comprise an openingwhich is intended for providing communication between a space which isformed between the insulating cover and the member on the partition wallside and a space on the motor side, and wherein the opening has anopening area which is not more than 10 square millimeters.
 4. Theelectric compressor according to anyone of claims 1 to 3, wherein theinsulating cover is provided integrally with a plurality of sealedterminals.